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18 Cards in this Set
- Front
- Back
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angle strain
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the strain induced in a molecule when bond angles are forced to deviate from the ideal 109 degree tetrahedral value
This is destabilizing |
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The more energy (strain) the compound contains, the more the _____ is released on _______
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energy (heat); combustion
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angle strain
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the strain due to expansion or compression of bond angles
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torsional strain
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the strain due to eclipsing of bonds on neighboring atoms
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steric strain
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strain due to repulsive interaction when atoms approach each other too closely
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What cycloalkane is the most strained of all the rings? Why?
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Cyclopropane; primarily because of the angle strain caused by its 60 degree C--C--C bond angles
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What are the most common cycloalkanes?
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substituted cyclohexanes, which occur widely in nature
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chain conformation
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a strain-free, three dimensional shape (e.g., in cycyclohexane)
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twist-boast conformation
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nearly free of strain (does have steric strain and torsional strait, however)
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Two hydrogens on the same face of a ring are always
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cis
regardless of whether they're axial or equatorial and regardless of whether they're adjacent |
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Two hydrogens on opposite faces of a ring are always
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trans
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Draw cyclohexane with its hydrogen bonds as a chair
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ring-flip
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interconversions
e.g., different chair conformations readily interconvert, exchanging axial and equatorial positions |
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The energy difference between axial and equatorial conformations is due to steric strain caused by:
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1,3-diaxial interactions
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decalin
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two fused cyclohexane rings joined to share wo carbon atoms
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Draw norbornane
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E(total) =
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E(bond stretching) + E(angle strain) + E(torsional strain) + E(van der Waals)
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